This invention relates to a process for producing barium hydroxide from barite.
Raw barium sulfide is produced in a known manner by the reduction of barium sulfate with coal. In the presence of moisture, raw barium sulfide is hydrated to form mixed crystals of barium hydroxide and barium hydrosulfide in accordance with the equation EQU 2 BaS + 2 H.sub.2 O .fwdarw. Ba(OH).sub.2 + Ba(SH).sub.2.
In accordance with a known proposal, this mixture is separated in that hydrated barium sulfide is oxidized with air and the reaction mixture, which contains difficulty soluble barium thiosulfate and barium polysulfide, is hot-leached to extract barium hydroxide, which is then precipitated by cooling. Another use of barium thiosulfate obtained as a by-product has not been disclosed (German Pat. No. 415,897).
It is also known to recover barium hydroxide and barium polysulfides by oxidizing solutions which contain barium sulfide at temperatures above 50.degree. C by an introducting of air, Barium hydroxide crystals are then precipitated by cooling and are removed. All or part of the mother liquor is recycled to the process. If the barium polysulfide which becomes available cannot be utilized, the process cannot be used in practice owing to the need to discard the barium polysulfide (German Pat. No. 519,981).